Daughter chromosomes

During anaphase, the two sets of daughter chromosomes separate and move toward the poles (anaphase A), and the poles move away from each other with an accompanying three- to fourfold elongation of the pole-to-pole distance by polar fibers but a shortening of the kinetochore fibers in anaphase B. 

The processes of meiosis and mitosis involve many motile events, from the separation of the daughter chromosomes to the final act of cell separation at cytokinesis (Wadsworth, 1993). DNA replication itself may be considered as a motile event, because the polymerase complex moves along the linear DNA. One of the most obvious motile events is the separation of the chromosomes along the mitotic spindle at anaphase. Details of the structure and polarity of microtubules in the spindle apparatus in meiosis and mitosis are known through electron and light microscopy, but it is not yet clear whether the chromosomes are pushed, pulled or... 

During the metaphase stage of mitosis, the daughter chromosomes normally begin to migrate toward the poles of the cell they are pulled toward the poles by microtubules, which... 

Type II topoisomerases are essential and function in replication, DNA repair, transcription, and chromosome segregation at mitosis.345,349 Yeast with a top2 mutation dies during mitosis with hopelessly entangled daughter chromosomes.353 A fluorescent antibody to eukaryotic topoisomerase II binds to chromosomes, probably at the bases of the radial loops... 

Chromatin occupies the remaining part of the nucleus and consists of DNA, RNA, and specialized proteins. Between cell divisions, chromatin is dispersed in the nucleus but, immediately before cell division, chromatin is arranged in granular bodies named chromosomes. After replication, daughter chromosomes are separated and distributed to daughter cells during the mitosis process, after which the chromatin is dispersed again. 

Watson and Crick (see Volume 1) immediately saw the relationship of the double helix to genetic replication. They proposed that each strand of the chromosome serves as a template to specify a new, complementary DNA strand. A template is a pattern for making something DNA acts as a template because each strand specifies the new daughter strand by base-pairing. This template feature makes DNA replication semiconservative after replication, each daughter chromosome has one strand of newly synthesized DNA and one strand of DNA from the parental chromosome. See Figure 8-6. 

Leading strand syntlresis can proceed all the way to the end of a chromosome however lagging strand synthesis can not. Consequently the 3 tips of each daughter chromosome would not be replicated. 

A generalized amplification of DNA gives rise to the polytene chromosomes found in the salivary glands of Drosophila. This process, termed polytenization, occurs when the DNA repeatedly replicates, but the daughter chromosomes do not separate. The result is an enlarged chro-... 

In mitosis, the replicated chromosomes are separated and evenly partitioned to two daughter chromosomes. This part of the cell cycle Is commonly divided Into four substages prophase, metaphase, anaphase, and telophase (see Figure 20-29). 

Proper Segregation of Daughter Chromosomes Is Monitored by the Mitotic Exit Network... 

The chromosome-segregation checkpoint prevents telophase and cytokinesis until daughter chromosomes have been properly segregated, so that the daughter cell has a full set of chromosomes (see Figure 21-32, [3]). 

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